| 摘要 |
An antenna receives electromagnetic radiation and furnishes a corresponding signal which after differentiation sets a first monostable multivibrator whose output lasts for several microseconds. A photodiode receives light signals. If the light signals are received within the time that the first monostable multivibrator is set, the generation of an alarm is inhibited, since substantially simultaneous reception of electromagnetic and light signals indicates either atmospheric disturbance or conventional weapons. In the absence of an inhibit signal, a second multivibrator is set for several milliseconds at the end of the setting of the first multivibrator. Any light received while the second multivibrator is set results in the furnishing of an alarm.
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